sched: idle: Avoid retaining the tick when it has been stopped

If the tick has been stopped already, but the governor has not asked to
stop it (which it can do sometimes), the idle loop should invoke
tick_nohz_idle_stop_tick(), to let tick_nohz_stop_tick() take care
of this case properly.

Fixes: 554c8aa8ecad (sched: idle: Select idle state before stopping the tick)
Cc: 4.17+ <stable@vger.kernel.org> # 4.17+
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 1a3e9bd..16f8414 100644 (file)
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -190,7 +190,7 @@ static void cpuidle_idle_call(void)
                 */
                next_state = cpuidle_select(drv, dev, &stop_tick);
 
-               if (stop_tick)
+               if (stop_tick || tick_nohz_tick_stopped())
                        tick_nohz_idle_stop_tick();
                else
                        tick_nohz_idle_retain_tick();